Packaging of tires in high stacks

ABSTRACT

Tires are packaged in a stack by positioning the tires on a packaging device having a set of parallel alignment rollers such that the rollers contact the treads of the tires to orient the tires as a stable stack, with the respective center axes of the tires being substantially parallel to the axes of the rollers. At least one of the rollers is rotated to rotate all of the tires in the stack about their respective center axes to align the center axes of all of the tires with a longitudinal axis of a cylinder defined by the stack. After stopping the rotation, the stack is compressed in the axial direction while the alignment of the tire axes with the cylinder axis is maintained. One or more bands are then wrapped around the stack while maintaining the compression. Then the compression is released to release the stack which remains restrained by the bands.

This application is a division of U.S. Ser. No. 11/011,613 filed Dec.15, 2004, and which claims priority under 35 U.S.C. §119 to PatentApplication Serial No. 03/14963 filed in France on Dec. 17, 2003.

BACKGROUND

The present invention concerns the technical sector of the packaging oftires which are not mounted on rims, also referred to as tire covers,with a view to transporting or storing the tires.

The incessant search for gains in productivity, coupled with a constantdesire to improve the working conditions of operators in this sector,has lead the various players in the industrial sector concerned tooptimize the logistic chain by acting on the storage conditions inindustrial warehouses, the transport, the loading and unloadingoperations and on the production of easily identifiable and movablebatches in line with the delivery requirements or the requirements foroptimization of the storage areas. These optimizations must also not beprejudicial to the integrity of the tires.

A first solution consists of using specially sized pallets for beingable to receive covers of varied dimensions and diameters. By way ofexample, a pallet commonly used in storage warehouses is described inthe application U.S. Pat. No. 5,259,325, in which the covers (unmountedtires) are stored in a stack or in a roll. Pallets of this type have theadvantage of constituting homogenous batches of covers, of being able tobe disposed on top of each other over great heights, of being able to bemanipulated by mechanical means of the fork lift truck type, and ofoffering good protection for the covers against external attacks. Theyare, on the other hand, less adapted to transport, in particular overlong distances, because of the small number of tires which they containhaving regard to their bulk, and the management of the returns of emptypallets.

For transporting over long distances, it will be sought to make thelargest number of covers enter a given volume, which may equally well bea lorry trailer, a maritime container, or a railway wagon.

Another solution commonly used consists of disposing the covers on topof each other with a particular arrangement known as a “fish bone” andputting the volume thus formed under compression so as to optimizeloading. These methods are described, by way of example, in the patentU.S. Pat. No. 5,092,106. Very effective for optimizing the volume to beloaded, they do, nevertheless, have the drawback of having to beproduced partly manually, in particular during unloading operations,which is a limiting factor from the ergonomic point of view because ofthe size and weight of the covers which it is possible to manipulate. Inaddition, this solution proves to be particularly inefficient in astorage warehouse because of the difficulty in handling and moving thebatches thus produced, because it imposes a break in packaging in thelogistic chain upstream and downstream of the transport operation, andbecause it is liable to cause mixing, should several sizes of cover bepackaged in the same load. Finally, it is not without effect on theintegrity of the tires because of the deformations which the latter mayundergo.

To this end it is remarkable to find that each of the solutionsmentioned above represents an optimum solution for a particular field,such as storage or transport, but rarely does the same technicalsolution prove to be advantageous over the entire logistic chain. Thisresults in introducing addition handlings, which partly ruin the gainsachieved by the choice of the solution most adapted to a particularpoint in the said chain.

This is the reason why intermediate solutions have been developed forthe purpose of finding an overall optimum. One of these solutionsconsists of packaging the envelopes in stacks, consisting in general ofaround ten covers disposed on top of each other so as to form a cylinderwith a vertical axis whose external surface is formed substantially bythe treads of each of the covers.

This solution has the advantage of forming homogeneous handling batcheswhich can easily be manipulated using adapted means. It thereby affordsan advantageous compromise for optimizing the logistic chain over allthe operations in the logistic chain, such as warehousing, the loadingand unloading operations, and also transport, particularly for largecovers which are difficult to manipulate manually, and provesparticularly well adapted when the transport is carried out in severalstages.

Once the stack is formed, the covers in the stack can be fixed togetherby a tie or strap as proposed in British Patent GB 166,747 or U.S. Pat.No. 1,507,376, by a shrink film as described in the U.S. Pat. No.4,858,415 or remain under the sole action of their own weight.

Industrial machines, of the type proposed by the patent U.S. Pat. No.3,955,491, have been developed to form stacks automatically in a firststep, and then secondly disposing one or more holding straps.

According to the size of the covers, it is possible to dispose one ormore stacks side by side on a flat pallet, generally non-recoverable, soas to optimize the size of the handling batches, or to treat the stackindependently.

However, the optimization of these solutions is partly related to thenumber of covers which it is possible to join together within the samestack and consequently the maximum height of the stack.

In particular, it may prove particularly advantageous to produce stackswhose height corresponds to the height of the volume used for transport,and the increase in height of the trailers used in road transportresults in wishing to use stacks of great height. “Great height” meansheights which may commonly range up to 3 m, or even more, in certainparticular cases.

It is found that these stacks are particularly tricky to manipulate inthe absence of means for fixing together the covers which make them up,because of the risk of possible falling of one or more covers duringhandling. Moreover, it is also found that, under the action of their ownweight or under the action of the tension of the straps, these stackshave an annoying tendency to deform and to exhibit a vertical projectionof their centre of gravity which is very off centre with respect to thecentre of their support base, consisting in this case of the contact ofthe first tire in the stack with the ground, and then leading to aninstability of the stack and a high and unacceptable risk of fallingover.

The object of the invention is to reduce these drawbacks.

SUMMARY OF THE INVENTION

Thus it has been shown that a precise alignment of the axes of thecovers constituting the stack, prior to any compression operation, makesit possible to obtain cylindrical stacks having very substantialvertical axes, allowing the production of stacks of great height whosecentre of gravity is projected substantially at the centre of thesupport base.

This precise alignment of the rotation axes of the tires is effectedbefore putting the stack under compression and after having depositedthe said tires on alignment rollers, by a rotation of all the tiresintended to constitute the stack. By proceeding thus, the contact areasbetween the sidewalls of two adjacent tires are adjusted in pairs sothat their rotation axes are precisely aligned, and all the radialstresses located at these interfaces and liable to subsequently deformthe stack are released.

The method of packaging tires in a stack then comprises the followingsteps:

-   -   disposing the tires of the same size and intended to constitute        a stack on a packaging device comprising a set of alignment        rollers, mounted for rotation about axes parallel to each other,        each of the rollers being intended to come into contact with the        treads of each of the said tires so as to hold the latter in a        stable fashion, the rotation axis of the tires being        substantially parallel to the axis of the alignment rollers,    -   then rotating at least one of the rollers, so as to rotationally        drive all the tires intended to constitute the stack about each        of their respective rotation axes until the rotation axes of        each of the tires is precisely aligned with the rotation axis        CC′ of the cylinder formed by the stack thus formed and whose        generatrices are tangent to the tread of each of the tires, and        parallel to the axis of the alignment rollers,    -   stopping the rotation of the alignment rollers,    -   compressing the stack in the axial direction using a compression        means whilst keeping the alignment produced in the previous        step,    -   disposing restraint means along the generatrices of the said        cylinder, for holding the stack under compression, and    -   releasing the action of the compression means in order to        release the stack.    -   discharging the stack.

The device for implementing this method comprises alignment means, meansof putting the stack of tires under compression and means of positioningrestraint means, and is characterized in that the alignment meansconsists of at least two alignment rollers mounted for rotation aboutaxes parallel to each other, each of the rollers being intended to comeinto contact with the treads of each of the said tires so as to hold thelatter in a stable fashion, at least one of the rollers being able todrive all the tires in rotation about their respective rotation axes.

The alignment rollers can be disposed horizontally or, according to avariant embodiment, vertically.

BRIEF DESCRIPTION OF THE DRAWINGS

The following description sets out to give a non-limiting exampleembodiment of the equipment whose use is in accordance with theinvention, relying on the figures, in which:

FIG. 1 depicts a schematic view of an industrial layout comprising apackaging device according to the invention;

FIG. 2 depicts a schematic view of a packaging device according to theinvention;

FIG. 3 a depicts a schematic view of a stack of tires produced with atraditional method, and

FIG. 3 b depicts a schematic view of a stack of tires produced with amethod of packaging tires in a stack according to the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Hereinafter, the elements of the equipment having identical functions,as depicted in FIGS. 1 to 3, will be designated by the same referencenumerals.

FIG. 1 presents a general schematic view of the production process inwhich the packaging machine is integrated. A lift truck 1 brings thetires packaged in vertical stacks P onto a supply belt 2. By “tires” ismeant tires not mounted on rims, also referred to as tire covers.

A loading and turning-over device 3 grips the stack P and deposits it inthe packaging device 3.

It should be noted, as described in detail hereinafter, that thispackaging device is disposed horizontally and that it is thereforenecessary to make the rotation axis of the covers pivot so as to bringthem into the horizontal position.

Moreover, when the stack to be packaged represents an excessively largenumber of covers for their stability to be controllable during theupstream transfer operations, it is entirely possible to introduce thecovers into the packaging device 4 in several loading operations.

Once the packaging operation has been executed on the packaging device4, the same device 3 serves to extract the stack P and, after rotation,to dispose it on the discharge belt 5.

FIG. 2 depicts a schematic view of a packaging device 4 according to theinvention, and configured in the following manner.

A frame 100, 101 supports a horizontal axis XX′ on which the twocompression plates 300 and 301 are disposed. These plates are able tomove in translation along the axis XX′ under the action of the rams 302and 303, and in rotation about the axis XX′ by means of a drive motor(not shown).

The compression plates support two alignment rollers 200 and 201 whoseaxes are parallel to each other and form a substantially horizontalplane. They are disposed symmetrically with respect to a vertical planepassing through the axis XX′.

The rollers 200 and 201 are mounted for rotation, and one of theserollers is provided with a drive motor (not shown). The other roller canalso be provided with a drive for driving it in rotation or be simplyfree to rotate about its axis.

The rollers 200 and 201 are also able to move in the horizontal planeand their ends move in slots 304 so that it is possible to vary theirseparation “e” according to the size of the tire to be packaged.

The means of positioning the restraint means uses a technology which iswidely commercially available, and consists of a fixed station 400 inwhich there are disposed a heat sealing strap dispenser, a travelingstrapping head and a tensioner and a heat-welding and cutting tool (notshown). Guide rails 401, 402, 404 and 405 are disposed on asubstantially horizontal plane passing substantially through the axisXX′ and through the equator of the stack and form a rectangularparallelepiped surrounding the stack P. The rails 404 and 405 aredisposed in the compression plates 300 and 301. It is thus possible,using the strapping head, to make the strap travel along the rails 401,404, 402, and 405 and then, by means of the tensioner, to put the strapunder tension by applying a calibrated force which will have the effectof releasing the strap from the rails and pressing it against twodiametrically opposed generatrices of the stack and on the flanks of thetwo tires situated at the two ends of the stack. The strap is then cutand the two ends are welded.

A restraint means of this type is sold by way of example by the companyDelonca under the trade name Jumbo.

The use of the device comprises a series of steps which will make itpossible to clarify the functions of each of the components describedabove.

In a first step the tires are deposited on the alignment rollers 200,201, arranging the rotation axes (center axes) of the tires in adirection substantially parallel to the alignment rollers.

The number of tires intended to constitute the stack is carefullydetermined so that the height of the stack once formed is substantiallyequal to the height of the most commonly used transport means. Thisheight varies commonly from 2.5 m to 3 m according to the type ofstandard used by the logistics and may in certain cases range up to 3.5m. Care will be taken to subtract the clearance necessary for performingthe loading and unloading operations by mechanical means. The length ofthe rollers 200, 201 and the spacing between the compression plates 300,301 will be determined accordingly.

It is then necessary to take account of the degree of compressionrequired for ensuring the cohesion of the stack once strapped.

Determined experimentally, this degree of compression varies from 10 to15% according to the dimensions. The criteria for determining theoptimum degree take into account:

-   -   the compression necessary for ensuring the cohesion of the stack        P throughout all the subsequent handling operations; ensuring        that at no time can sliding occur between the sidewalls of the        tires and then destroy the coaxiality of the stack with the        consequence of introducing an imbalance factor when the stack is        stored vertically,    -   the deformations under stress (temporary) of the covers and        principally the deformation of the tires situated at the two        ends of the stack.

It proves particularly useful, as will be seen below, to make the axisof the stack correspond with the rotation axis XX′ of the compressionplates 300, 301, so as to ensure there is as even a positioning of therestraint means as possible. By judiciously preadjusting the separation“e” between the rollers 200 and 201 according to the size to bepackaged, it is ensured that the axes of the tires and the axis of thestack will be substantially aligned with the axis XX′.

Resting through two generatrices of their tread on the alignment rollers200, 201, it will be remarked that, in this arrangement, the tires areheld in a stable fashion because their centers of gravity are situatedsubstantially on a vertical plane passing through the axis XX′ andbetween the alignment rollers 200 and 201.

Before the alignment operation proper, it may prove useful to re-formthe stack and position the tires in as even a manner as possible. Tothis end the compression plates 300, 301 will be brought together afirst time so as to cause a slight compression of the stack and then thepressure will be released by positioning the plates as close as possibleto the point of last contact between their respective internal faces andthe sidewalls of the tires situated at the two ends of the stack.

The rotation of one of the alignment rollers will cause the rotation ofeach of the tires about its rotation axis. The effect of this overallmovement is to precisely align each of the tires with respect to eachother and to ensure that the rotation axis of each of the tires mergeswith the longitudinal axis CC′ of a cylinder formed by the stack thusformed and whose generatrices are tangent to the tread of each of thetires, and parallel to the axis of the alignment rollers 200, 201, inorder to obtain the maximum required concentricity. It is the precisionof this alignment, combined with the compression in order to preservethe effects thereof, which procures the required stability for thestack.

This operation is completed after having made the stack of tires performa small number of turns; around ten turns seems experimentally to givesatisfaction.

Once the alignment is obtained it is necessary to compress the stack andto bring together the two compression plates 300, 301.

It should be remarked, however, that it may be particularlyadvantageous, once this alignment operation is performed, to prevent thetires from losing their alignments by lack of axial cohesion. This isthe reason why it was suggested above to position the compression plates300, 301 as close as possible to the external faces of the tiressituated at the two ends of the stack.

However, so as to avoid any friction which may occur during the phase ofalignment between the internal face of the compression plates and theexternal sidewalls of the two tires situated at the two ends of thestack and liable to impair their correct alignment, it is particularlyadvantageous to provide the internal face of the said plates withdevices assisting sliding. This device may consist of a film of materialwith a low resistance to friction such as a film ofpolytetrafluoroethylene or a set of bearings.

The compression of the stack is effected by axially actuating the rams302, 303 and moving the plates 300, 301. It may prove judicious tocompress the stack to a value slightly greater than the final valuedesired so as to take account of the elasticity of the straps.

Care will be taken during this operation not to compromise the alignmentachieved during the previous step.

Once the stack is put under compression and held between the two plates300, 301, it is then possible to dispose the restraint means so as toclamp the movements of the stack in the axial direction. In order toensure the best evenness of the clamping of the stack, it is recommendedto dispose at least two straps so that the outlines of the straps on thesidewalls situated at the two ends of the stack delimit substantiallyequal sectors. Thus two straps will be disposed with an angle of 90°,three straps with an angle of 60° and possibly four straps with an angleof 45°.

Care will be taken that this strap installation tension is constant.

It also proves to be particularly advantageous to be able to turn thestack about its axis CC′ so as to dispose the restraint means in as evena manner as possible. To this end, the simultaneous rotation of theplates turning about the axis XX′, substantially merged with the axisCC′ of the stack, makes it possible to dispose the stack at as manyangular positions as there are restraint means to be positioned, whilstkeeping the stack under compression in order to prevent any radialmovement of the tires with respect to each other. To this end the plates300, 301 each comprise as many sets of rails as necessary to ensure thecontinuity of the guidance of the strapping head, that is to say, in theconfiguration serving as a support for this description, two railsdisposed at 90°, 403, 404, 405. In the case it is desired to disposethree straps, it should be convenient to realize on each plate 300, 301,three rails disposed at 60°.

The choice of the straps 407 (FIG. 3B) is adapted according to the sizeto be packaged. Namely that the width and thickness will be determinedaccording to the stresses undergone by the strap, but also according tothe pressure which it is possible to exert on the sidewalls of the tiressituated at the two ends of the stack without causing permanentdeformations. Thus a 25 mm strap will be chosen for a size of theprivate car type and a 35 mm strap for a size of the heavy goods vehicletype.

The strap can consist of a flexible material such as polyester,polyamide or polyethylene. Metallic ties can possibly be used in theheavy goods vehicle size for preference.

Once the restraint means are fastened, the plates 300, 301 for puttingthe stack under compression are returned to their initial angularposition and by distancing the said compression plates the stack P isreleased, which it is then possible to discharge with an unloading means3 and to replace in a vertical position.

The stack thus formed has sufficient internal cohesion to be able toundergo all subsequent handlings without harmful changes.

FIGS. 3A and 3B depict a stack as obtained with traditional means (3A)and a stack obtained with the method as described above (3B).

The configuration of the device which served as a support for thedescription of the invention corresponds to a preferential embodiment.It should be noted nevertheless that it is possible to proposeequivalent embodiments whilst remaining within the scope of theteachings proposed by the present invention.

A person skilled in the art will thus be able to adapt the devicewithout difficulty so as to dispose the two alignment rollers 200, 201horizontal and parallel to each other but forming a plane making anangle with the horizontal.

Likewise, whilst keeping the alignment rollers horizontal and parallelto each other, it is possible to arrange a device comprising threerollers or even more.

Another configuration consists of disposing the rollers vertically,which may constitute an advantage in terms of handling and organizationof the packaging workshop.

In this context it is necessary to use at least three alignment rollersso as to grip the stack to be packaged in a stable fashion. Theserollers will be disposed so that the line of the intersection of theaxes of the alignment rollers with a horizontal plane forms asubstantially regular polygon. It will be necessary to provide amechanism for bringing in and withdrawing the rollers in the radialdirection so as to release a space for introducing and extracting thetires from the alignment device. Finally, the restraint device will bepositioned accordingly.

In this configuration it will also be necessary to adapt the radialpressure of the rollers On the treads of the tires so as to compel thelatter to be aligned correctly in a radial direction whilst combatingthe friction forces existing between the sidewalls of each of the tiresin the stack.

The choice of strapping passing through the diametrically opposedgeneratrices remains the best adapted embodiment. However, it ispossible to produce strapping by making the strap pass along a linepassing through an external generatrix of the stack, through the radialpathways adjoining this generatrix and situated on the flanks of the twotires situated at the two axial ends of the stack, and through theinternal part of the stack. This makes it necessary to dispose a railpassing through the inside of the stack and to remove it at each end ofthe cycle, which is not without repercussion on the overall bulk and onthe cycle time of the packaging device.

1. Apparatus for packaging tires in a stack, comprising: a packagingdevice including a plurality of alignment rollers rotatable aboutrespective parallel roller axes and arranged to contact the tire treadsto orient the tires as a stable stack, with the respective center axesof the tires being substantially parallel to the roller axes, at leastone of the rollers being drivable in rotation about its respective axisto rotate all of the tires about their respective center axes; acompression mechanism arranged to compress the stack in the axialdirection; and a restraint-applying mechanism arranged to apply arestraint around the stack prior to release of the compression by thecompression mechanism.
 2. Apparatus according to claim 1 wherein thealignment rollers are disposed substantially horizontally.
 3. Apparatusaccording to claim 1 wherein there are at least three alignment rollersand they are disposed substantially vertically.
 4. Apparatus accordingto claim 2 wherein the compression mechanism includes a pair of plateshaving mutually facing faces arranged substantially parallel to oneanother and substantially perpendicular to the roller axes; at least oneof the plates being movable in translation toward the other plate alongan axis parallel to the roller axes.
 5. Apparatus according to claim 4wherein each of the mutually facing faces is covered with ananti-friction film.
 6. Apparatus according to claim 4 wherein each ofthe mutually facing faces carries bearings to minimize friction betweenthe tires and the faces.
 7. Apparatus according to claim 2 wherein therestraint-applying mechanism is arranged to apply the restraintstructure under tension along a line passing through two external anddiametrically opposed generatrices of a cylinder defined by the stack oftires and along respective sidewalls of two end-most tires of the stack.8. Apparatus according to claim 2 wherein the restraint-applyingmechanism is arranged to apply the restraint structure under tensionalong a line passing through an external generatrix of the stack,through radial pathways situated along respective sidewalls of twoend-most tires of the stack, and through the interior of the stack. 9.Apparatus according to claim 7 wherein the compression mechanismincludes a pair of plates having mutually facing faces arrangedsubstantially parallel to one another and substantially perpendicular tothe roller axes; at least one of the plates being movable in translationtoward the other plate along an axis parallel to the roller axes, theplates being rotatable together about an axis oriented parallel to theroller axis to circumferentially turn the stack.
 10. Apparatus accordingto claim 8 wherein the compression mechanism includes a pair of plateshaving mutually facing faces arranged substantially parallel to oneanother and substantially perpendicular to the roller axes; at least oneof the plates being movable in translation toward the other plate alongan axis parallel to the roller axes, the plates being rotatable togetherabout an axis oriented parallel to the roller axis to circumferentiallyturn the stack.
 11. Apparatus according to claim 9 wherein a distancebetween the alignment rollers is adjustable to conform to the tire size.12. Apparatus according to claim 10 wherein a distance between thealignment rollers is adjustable to conform to the tire size.